WAFFLE GURGLE FLUTE
The neck of a latex balloon droops into the upper end of this flute-like instrument. Blowing through the balloon-neck causes it to rasp and razz just inside the tube, agitating the air in an unrefined sort of way. Given this generalized turbulence, the air column naturally highlights its own resonance frequencies. The resulting tone is by no means clean and clear, but the ear does recognize the pitch of that resonance. By covering and uncovering the toneholes you can change the resonance pitch just as on a flute, and thus play melodies. For amplification (not required, but helpful sometimes), a small microphone can be lodged in a hole near the mouthpiece.
A video of this instrument can be found among the demonstrations in this youtube playlist.